The present invention relates to a color filter which can improve display quality and further concerns an optical display device using the same.
Conventionally, as disclosed in Japanese Laid-Open Patent Publication No. 21992/1996 (Tokukaihei 8-21992, published on Jan. 23, 1996), a color filter used for a color liquid crystal display device has been provided with, for example, a stripe pattern or a dot pattern of red (hereinafter, referred to as R), green (hereinafter, referred to as G), and blue (hereinafter, referred to as B), that serves as coloring layers of color filter picture elements, on a transparent support.
Between the color filter picture elements and on a frame (outer frame), a black mask (also referred to as a black matrix) is disposed to improve contrast and display quality.
The black mask is disposed to provide a black color similar to a black display and is formed by patterning a black paste layer or a metal layer. Further, in some cases, a resin such as an acrylic resin having superior transparency is applied as an overcoat layer on a pattern including stripes of R, G, and B.
As for such a color filter, it has been considered to omit a step of manufacturing a black mask to reduce the cost. Conventionally, the following method has been well known for omitting the step of manufacturing a black mask: as shown in FIG. 20, among the coloring layers of R, G, and B corresponding to the R, G, and B color filter picture elements, that are used in a picture element part 31 acting as a display section, the coloring layers of R and B, or the coloring layers of R, G, and B are overlaid to one another, and the overlaid parts are displayed in black, so that a frame 30 is formed.
However, in the above conventional method, colors are overlaid to one another so as to be displayed in black; thus, the more colors are overlaid, the larger a thickness is. Hence, as shown in FIG. 20, height differences indicated by arrows 32 appear between the picture element part 31 and the frame 30 on a driving side, so that a cell thickness becomes uneven. Therefore, in a portion of the picture element part 31 that is adjacent to the frame 30, an amount of light is smaller than that of the center, resulting in degradation in display quality of the picture element part 31.
Hence, in order to overcome the uneven cell thickness caused by the height difference, it has been considered to form the frame by extending a stripe having the same pitch width as the picture element; however, a belt having the same width as the picture element is visually observed, so that display quality is degraded (stripes are readily found by visual observation because the stripe has a large width and the same pitch as the picture elements corresponding to pixels).
In order to overcome the above problem, Japanese Laid-Open Patent Publication No. 62768/1998 (Tokukaihei 10-62768, published on Mar. 6, 1998) discloses that each of the picture elements corresponding to the colors has a pitch and a width of 100 xcexcm or less in the frame, so that display quality can be improved.
However, in the conventional color filter, each of the picture elements, which correspond to the different colors, has the same width in the frame. Thus, the area ratio of the picture elements is 1:1:1, and the colors are evenly displayed in the frame. Therefore, in the conventional art, the colors go out of balance between the frame and the display section, or between the frame and a cabinet of the color liquid crystal display device, resulting in degradation in appearance during the operation of the color liquid crystal display device.
The objective of the present invention is to omit a step of manufacturing a black matrix so as to reduce the cost, and to provide a color filter for an optical display device that realizes an excellent appearance upon providing a display.
In order to achieve the above objective, a color filter of the present invention includes a color filter display which consists of picture elements corresponding to three colors and displays an image, and a color filter frame which serves as a frame of the color filter display and consists of picture elements corresponding to at least two of the three colors, the color filter frame having an area ratio of the picture elements that is different from that of the color filter display, the picture elements corresponding to different colors.
Further, in order to achieve the above objective, another color filter of the present invention includes a color filter display which consists of picture elements corresponding to three colors and displays an image, and a color filter frame which serves as a frame of the color filter display and consists of picture elements corresponding to at least two of the three colors, the color filter frame having an area ratio of the picture elements that is set so as to allow the color filter frame to have a desired color, the picture elements corresponding to different colors.
According to this arrangement, the color filter display consists of the picture elements corresponding to three colors, and the color filter frame serving as a frame of the color filter display consists of picture elements corresponding to at least two of the three colors of the color filter display.
In a conventional color filter, for example, the color filter frame consists of picture elements corresponding to three colors, and each of the picture elements has a line width of 100 xcexcm or less. With this arrangement, the picture elements of the color filter frame cannot be individually recognized so as to be observed as a single color. Namely, such an arrangement of the picture elements acts as a black matrix in the color filter frame, so that it is not necessary to provide a metal layer and the like as a black matrix. Thus, it is possible to omit the step of manufacturing a black matrix in the color filter frame so as to reduce the cost.
However, the conventional arrangement has the following problem. A conventional color filter frame simply consists of picture elements corresponding to two colors, so that an area ratio of the picture elements corresponding to different colors is 1:1:1, which is equal to that of the color filter display. Therefore, only a single kind of color can be developed, so that a variety of colors cannot appear in the color filter frame. Hence, in a color liquid crystal display device using the conventional color filter, the appearance is spoiled during an operation and a displayed image becomes less easy to see.
Meanwhile, with the arrangement of the present invention, in the color filter frame, an area ratio of the picture elements corresponding to different colors is different from that of the color filter display. Or in the color filter frame, an area ratio of the picture elements corresponding to different colors is set so as to allow the color filter frame to have a desired optical property.
To be specific, in the color filter display, an area ratio of picture elements corresponding to different colors is 1:1:1; meanwhile, the area ratio is, for example, 1:1:2 in the color filter frame. The area ratio is set so as to allow the color filter frame to have a desired optical property such as a reflectivity and color.
With this arrangement, it is possible to develop a desired color in the color filter frame so as to improve a degree of freedom in arranging colors for the color filter frame. Hence, with the color filter having the above arrangement, it is possible to arrange a suitable color for the color filter frame, based on a color displayed in the operation of each optical display device. Thus, it is possible to prevent a spoiled appearance during the operation and to prevent a displayed image from being less easy to see.
Further, in order to achieve the aforementioned objective, an optical display device of the present invention includes a color filter having a color filter display which consists of picture elements corresponding to three colors and displays an image, and a color filter frame which serves as a frame of the color filter display and consists of picture elements corresponding to at least two of the three colors, the color filter frame having an area ratio of the picture elements that is different from that of the color filter display, the picture elements corresponding to different colors.
With this arrangement, in the color filter frame, an area ratio of the picture elements corresponding to different colors is different from that of the color filter display, and the area ratio is set so as to allow the color filter frame to have a desired color. Thus, it is possible to develop a desired color in the color filter frame so as to improve a degree of freedom in arranging colors for the color filter frame.
Therefore, in the optical display device provided with the color filter having the above arrangement, it is possible to arrange a suitable color for the color filter frame, based on a color displayed in the operation of each optical display device. Hence, it is possible to prevent the spoiled appearance during the operation and to prevent a displayed image from being less easy to see.
For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.